I was recently introduced to a study involving Corn snakes, where they provided daily UV exposure. The only Measurable benefit was the that the Snakes calcium and D3 levels were noticeably higher than the non UV exposed control group( I'm talking 50-65% higher). That being said captive snakes to not REQUIRE UV lights, however I am toying with the idea of UV exposure for females during the building phase of breeding to see if it cuts down on the instances of "Snowflaking" in the clutches produced.
But generally i do not provide a UV source for my Ball Pythons.